Neighbourhood-level deprivation is associated with preterm birth; preterm birth rates are also higher for some, but not all migrant groups. We studied the impact of neighbourhood characteristics (a deprivation score and the proportion of foreign-born residents) on singleton preterm birth in the French district of Seine-Saint-Denis for women born in France, North Africa, sub-Saharan Africa and other countries. Multilevel logistic regression models were adjusted for maternal demographic and health care characteristics. For women born in France, the preterm birth rate rose with neighbourhood deprivation quintile (3.8% in the first to 5.7% in the fifth, adjusted odds ratio: 1.40 [95% confidence interval 1.14, 1.72]) and with increasing proportions of foreign-born residents. Preterm birth rates were not higher in more deprived neighbourhoods for women born outside of France and were lower in neighbourhoods with more foreign-born residents; in multilevel models, the inverse association with deprivation remained significant for women from sub-Saharan Africa. Area-based deprivation measures should be used with caution in populations with large numbers of migrants. These results raise questions about the health benefits of clustering for migrant communities as well as the negative consequences of acculturation.